1. Field of Invention
The invention relates to a process for reducing a monitor's power consuming, and more particularly, to a process for reducing the power consuming of a monitor which works in a DPMS mode.
2. Related Art
Presently, a monitor has to meet the requirements of Energy Star established by the U.S. Environmental Protection Agency and the Display Power Management Standard (DPMS) established by the Video Electronics Standards Association (VESA) to be qualified as an energy saving monitor. The DPMS provides a power management function for the monitor, which will process an energy saving mode when there is no signal input to the monitor so the electricity can be saved.
There are four modes in the power management for a monitor, which are normal, standby, DPMS and off. As shown in Table 1, these four modes correspond to different status of signal processor and micro-controller of the monitor and different power consuming extents respectively.
TABLE 1Signal processorMicro-controllerPower consumingNormalOnOnHighStandbyOffSleepLowDPMSSleepOnMediumOffOffSleepLow
The normal mode is when the monitor displays. A monitor like a liquid crystal display usually has different status in its normal mode, such as a television mode and a computer mode, which have different signal sources respectively. The Off mode is when all the signal sources are closed; therefore the signal processor which is responsible for detecting the signal will also be off to save the energy. In addition, when the monitor switched from one mode to another, the monitor must switch the signal source. In this switching process, the monitor is in the DPMS mode. At this time, the monitor will try to detect the signal source. While there is no signal detected, there is no display in the monitor. But when there is a signal detected, the monitor will be in the switched mode and display.
In the prior art, the signal processor is used for detecting the signal. Therefore in the DPMS mode, the signal processor is in the sleep status. However, in order to accelerate the image output when a signal is detected, the micro-controller must be on so the monitor will certainly consume some energy. If the signal processor does not detect a signal for certain of time, the energy consuming in the DPMS mode will be tremendous. Therefore, how to reduce the energy consuming in the DPMS mode becomes a problem.